package com.hmdp.service.impl;

import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSON;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;
import java.util.stream.Stream;


import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    private static final ExecutorService executorService = Executors.newFixedThreadPool(10);

    @Autowired
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
        //Shop shop = cachePenetratio(id);
        Shop shop = cacheClient.cachePenetratio(id, Shop.class, CACHE_SHOP_KEY, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //互斥锁解决缓存击穿
//        Shop shop = cacheBreakdown(id);

        //逻辑过期解决缓存击穿
//        Shop shop = logicalExpiration(id);
//        if (shop == null){
//            return Result.fail("店铺不存在");
//        }
        return Result.ok(shop);
    }

    private Shop cacheBreakdown(Long id){
        //1.从redis查询
        String s = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
        //2.判断是否存在
        if (StrUtil.isNotBlank(s)){
            //存在
            Shop shop = JSONUtil.toBean(s, Shop.class);
            return shop;
        }
        if (s != null) {
            //是空值，返回错误
            return null;
        }
        //4.获取锁
        Shop shop = null;
        try {
            if (!tryLock(LOCK_SHOP_KEY)){
                //4.1 判断是否获取锁成功
                //4.2不成功
                Thread.sleep(50);
                return cacheBreakdown(id);
            }
            //4.3成功，查询数据库
            //获取锁成功后再次查询一下redis，防止另外线程写入redis之后释放锁正好被此线程拿到锁
            if (StrUtil.isNotBlank(s)){
                //如果查到缓存存在，就不用再走数据库了
                shop = JSONUtil.toBean(s, Shop.class);
                return shop;
            }
            shop = getById(id);
            //5.数据库不存在，返回错误
            if (shop == null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, "", RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL,TimeUnit.MINUTES);
        } catch (InterruptedException e) {
           throw new RuntimeException(e);
        }finally {
            //释放锁
            unLock(LOCK_SHOP_KEY);
        }
        //7.返回
        return shop;
    }
    private Shop cachePenetratio(Long id){
        //1.从redis查询
        String s = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
        //2.判断是否存在
        if (StrUtil.isNotBlank(s)){
            //存在
            Shop shop = JSONUtil.toBean(s, Shop.class);
            return shop;
        }
        if (s != null) {
            //是空值，返回错误
            return null;
        }
        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.数据库不存在，返回错误
        if (shop == null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, "", RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        //6.存在，写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL,TimeUnit.MINUTES);
        //7.返回
        return shop;
    }

    private Shop logicalExpiration(Long id){
        //1.从redis查询
        String s = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
        if (StrUtil.isBlank(s)){
            return null;
        }
        //2.拿到缓存
        RedisData redisData = JSONUtil.toBean(s, RedisData.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        //3.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //未过期，直接返回店铺信息
            return shop;
        }
        //5.已过期，获取互斥锁
        if (tryLock(LOCK_SHOP_KEY+id)){
            //6.获取锁成功开启新线程，查询数据库，写入redis
            //再次检查缓存是否过期
            if (expireTime.isAfter(LocalDateTime.now())){
                //未过期，直接返回店铺信息，不用再查数据库了
                return shop;
            }
            executorService.submit(()->{
                try {
                    saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    //7.释放锁
                    unLock(LOCK_SHOP_KEY+id);
                }
            });
        }
        //未获取，返回信息
        return shop;

    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", LOCK_SHOP_TTL, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(flag);
    }

    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    private void saveShop2Redis(Long id,Long ttl) {
        //1.查询店铺数据
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(ttl));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));

    }

    @Transactional
    @Override
    public Result update(Shop shop) {
        //1.更新数据库
        updateById(shop);
        //2.删除redis
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if (x == null || y == null){
            //不需要坐标查询，按数据库查询
            // 根据类型分页查询
            Page<Shop> page =query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        //3.查询redis,按照具体距离排序分页。结果：shopId，distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),//5000m默认单位是米
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );

        //4.解析id
        if (results == null){
            return Result.ok();
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> content = results.getContent();
        if (content.size() <= from){
            return Result.ok(Collections.emptyList());
        }
        //4.1截取从from到end的部分
        List<Long> ids = new ArrayList<>(content.size());
        Map<String, Distance> distanceMap = new HashMap<>(content.size());
        content.stream().skip(from).forEach(result ->{
            //获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        //5.根据id批量查询店铺
        String idStr = StrUtil.join(", ", ids);
        List<Shop> shopList = query().in("id", ids).last("ORDER BY FIELD(id, " + idStr + ")").list();
        for (Shop shop : shopList) {
            //6.封装距离
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shopList);
    }
}
